BIOGEN INC

Ticker: BIIB CUSIP: 09062X103 Class: COM

PRIMECAP MANAGEMENT CO/CA/'s Holding History (CIK: 0000763212)

Note: Option positions (PUT/CALL) are excluded.

Q4 2025

Shares 14,757,997 Value ($000) $2,597,260 Avg Close $163.37 Range $138.00 - $185.17

Q3 2025

Shares 14,954,697 Value ($000) $2,094,854 Avg Close $135.17 Range $121.05 - $150.28

Q2 2025

Shares 15,802,122 Value ($000) $1,984,589 Avg Close $124.60 Range $110.04 - $137.32

Q1 2025

Shares 15,943,259 Value ($000) $2,181,676 Avg Close $142.96 Range $128.51 - $157.09

Q4 2024

Shares 16,046,209 Value ($000) $2,453,786 Avg Close $168.67 Range $145.07 - $195.00

Q3 2024

Shares 16,315,079 Value ($000) $3,162,515 Avg Close $209.21 Range $188.78 - $238.00

Q2 2024

Shares 16,338,294 Value ($000) $3,787,543 Avg Close $217.32 Range $189.44 - $237.54

Q1 2024

Shares 16,220,716 Value ($000) $3,497,673 Avg Close $234.20 Range $211.02 - $268.30

Q4 2023

Shares 16,264,481 Value ($000) $4,208,760 Avg Close $245.62 Range $220.86 - $269.43

Q3 2023

Shares 16,012,566 Value ($000) $4,115,390 Avg Close $267.47 Range $251.85 - $287.60

Q2 2023

Shares 16,025,876 Value ($000) $4,564,971 Avg Close $297.86 Range $273.39 - $319.76

Q1 2023

Shares 16,001,166 Value ($000) $4,448,804 Avg Close $276.70 Range $254.80 - $295.90

Q4 2022

Shares 15,700,576 Value ($000) $4,347,804 Avg Close $282.44 Range $250.31 - $311.88

Q3 2022

Shares 15,741,715 Value ($000) $4,203,038 Avg Close $212.38 Range $193.65 - $283.44

Q2 2022

Shares 15,726,526 Value ($000) $3,207,268 Avg Close $204.43 Range $187.16 - $225.50

Q1 2022

Shares 15,834,606 Value ($000) $3,334,768 Avg Close $217.46 Range $192.67 - $249.00

Q4 2021

Shares 15,757,405 Value ($000) $3,780,517 Avg Close $257.12 Range $221.72 - $290.76

Q3 2021

Shares 16,258,915 Value ($000) $4,601,110 Avg Close $327.75 Range $282.64 - $372.12

Q2 2021

Shares 16,458,506 Value ($000) $5,699,087 Avg Close $302.94 Range $257.03 - $468.55

Q1 2021

Shares 16,758,256 Value ($000) $4,688,122 Avg Close $269.69 Range $238.40 - $296.38

Q4 2020

Shares 15,822,066 Value ($000) $3,874,191 Avg Close $259.08 Range $223.25 - $363.92

Q3 2020

Shares 15,696,704 Value ($000) $4,452,841 Avg Close $278.91 Range $261.87 - $312.00

Q2 2020

Shares 15,631,932 Value ($000) $4,182,323 Avg Close $300.59 Range $257.60 - $350.24

Q1 2020

Shares 15,965,989 Value ($000) $5,051,320 Avg Close $303.47 Range $262.25 - $374.99

Q4 2019

Shares 15,189,481 Value ($000) $4,507,175 Avg Close $277.46 Range $219.70 - $318.00

Q3 2019

Shares 14,260,012 Value ($000) $3,320,016 Avg Close $232.85 Range $215.78 - $246.99

Q2 2019

Shares 14,554,002 Value ($000) $3,403,744 Avg Close $230.90 Range $219.20 - $245.35

Q1 2019

Shares 14,586,382 Value ($000) $3,447,929 Avg Close $314.89 Range $216.12 - $344.00

Q4 2018

Shares 14,716,217 Value ($000) $4,428,404 Avg Close $319.14 Range $278.46 - $358.41

Q3 2018

Shares 14,873,796 Value ($000) $5,255,061 Avg Close $344.30 Range $288.13 - $388.67

Q2 2018

Shares 14,921,936 Value ($000) $4,330,943 Avg Close $281.15 Range $249.17 - $310.91

Q1 2018

Shares 14,953,231 Value ($000) $4,094,494 Avg Close $310.41 Range $259.76 - $370.57

Q4 2017

Shares 15,109,231 Value ($000) $4,813,348 Avg Close $320.80 Range $301.81 - $348.84

Q3 2017

Shares 15,212,914 Value ($000) $4,763,468 Avg Close $296.11 Range $269.50 - $330.00

Q2 2017

Shares 15,391,401 Value ($000) $4,176,611 Avg Close $264.42 Range $244.28 - $291.90

Q1 2017

Shares 15,477,424 Value ($000) $4,231,837 Avg Close $282.75 Range $260.50 - $301.42

Q4 2016

Shares 15,584,387 Value ($000) $4,419,420 Avg Close $296.43 Range $268.00 - $329.83

Q3 2016

Shares 15,693,905 Value ($000) $4,912,663 Avg Close $296.18 Range $240.07 - $333.65

Q2 2016

Shares 16,024,861 Value ($000) $3,875,132 Avg Close $263.54 Range $223.02 - $292.69

Q1 2016

Shares 16,246,726 Value ($000) $4,229,348 Avg Close $264.15 Range $242.07 - $301.02

Q4 2015

Shares 15,810,625 Value ($000) $4,843,585 Avg Close $287.35 Range $254.00 - $311.65

Q3 2015

Shares 15,843,460 Value ($000) $4,623,280 Avg Close $330.23 Range $265.00 - $412.24

Q2 2015

Shares 16,501,541 Value ($000) $6,665,632 Avg Close $401.33 Range $368.88 - $432.88

Q1 2015

Shares 16,558,763 Value ($000) $6,991,772 Avg Close $394.14 Range $334.40 - $480.18

Q4 2014

Shares 17,170,693 Value ($000) $5,828,592 Avg Close $323.51 Range $290.85 - $361.93

Q3 2014

Shares 17,216,631 Value ($000) $5,695,434 Avg Close $329.72 Range $298.31 - $349.00

Q2 2014

Shares 17,258,311 Value ($000) $5,441,718 Avg Close $300.97 Range $272.02 - $322.25

Q1 2014

Shares 17,502,106 Value ($000) $5,353,369 Avg Close $317.43 Range $270.62 - $358.89

Q4 2013

Shares 17,777,602 Value ($000) $4,970,120 Avg Close $258.65 Range $221.07 - $298.82

Q3 2013

Shares 17,968,172 Value ($000) $4,326,017 Avg Close $223.81 Range $203.55 - $248.95

Q2 2013

Shares 18,246,809 Value ($000) $3,926,713 Avg Close $213.68 Range $191.80 - $242.64

Period	Shares	Value ($000)	Average Close	Price Range
Q4 2025	14,757,997	$2,597,260	$163.37	$138.00 - $185.17
Q3 2025	14,954,697	$2,094,854	$135.17	$121.05 - $150.28
Q2 2025	15,802,122	$1,984,589	$124.60	$110.04 - $137.32
Q1 2025	15,943,259	$2,181,676	$142.96	$128.51 - $157.09
Q4 2024	16,046,209	$2,453,786	$168.67	$145.07 - $195.00
Q3 2024	16,315,079	$3,162,515	$209.21	$188.78 - $238.00
Q2 2024	16,338,294	$3,787,543	$217.32	$189.44 - $237.54
Q1 2024	16,220,716	$3,497,673	$234.20	$211.02 - $268.30
Q4 2023	16,264,481	$4,208,760	$245.62	$220.86 - $269.43
Q3 2023	16,012,566	$4,115,390	$267.47	$251.85 - $287.60
Q2 2023	16,025,876	$4,564,971	$297.86	$273.39 - $319.76
Q1 2023	16,001,166	$4,448,804	$276.70	$254.80 - $295.90
Q4 2022	15,700,576	$4,347,804	$282.44	$250.31 - $311.88
Q3 2022	15,741,715	$4,203,038	$212.38	$193.65 - $283.44
Q2 2022	15,726,526	$3,207,268	$204.43	$187.16 - $225.50
Q1 2022	15,834,606	$3,334,768	$217.46	$192.67 - $249.00
Q4 2021	15,757,405	$3,780,517	$257.12	$221.72 - $290.76
Q3 2021	16,258,915	$4,601,110	$327.75	$282.64 - $372.12
Q2 2021	16,458,506	$5,699,087	$302.94	$257.03 - $468.55
Q1 2021	16,758,256	$4,688,122	$269.69	$238.40 - $296.38
Q4 2020	15,822,066	$3,874,191	$259.08	$223.25 - $363.92
Q3 2020	15,696,704	$4,452,841	$278.91	$261.87 - $312.00
Q2 2020	15,631,932	$4,182,323	$300.59	$257.60 - $350.24
Q1 2020	15,965,989	$5,051,320	$303.47	$262.25 - $374.99
Q4 2019	15,189,481	$4,507,175	$277.46	$219.70 - $318.00
Q3 2019	14,260,012	$3,320,016	$232.85	$215.78 - $246.99
Q2 2019	14,554,002	$3,403,744	$230.90	$219.20 - $245.35
Q1 2019	14,586,382	$3,447,929	$314.89	$216.12 - $344.00
Q4 2018	14,716,217	$4,428,404	$319.14	$278.46 - $358.41
Q3 2018	14,873,796	$5,255,061	$344.30	$288.13 - $388.67
Q2 2018	14,921,936	$4,330,943	$281.15	$249.17 - $310.91
Q1 2018	14,953,231	$4,094,494	$310.41	$259.76 - $370.57
Q4 2017	15,109,231	$4,813,348	$320.80	$301.81 - $348.84
Q3 2017	15,212,914	$4,763,468	$296.11	$269.50 - $330.00
Q2 2017	15,391,401	$4,176,611	$264.42	$244.28 - $291.90
Q1 2017	15,477,424	$4,231,837	$282.75	$260.50 - $301.42
Q4 2016	15,584,387	$4,419,420	$296.43	$268.00 - $329.83
Q3 2016	15,693,905	$4,912,663	$296.18	$240.07 - $333.65
Q2 2016	16,024,861	$3,875,132	$263.54	$223.02 - $292.69
Q1 2016	16,246,726	$4,229,348	$264.15	$242.07 - $301.02
Q4 2015	15,810,625	$4,843,585	$287.35	$254.00 - $311.65
Q3 2015	15,843,460	$4,623,280	$330.23	$265.00 - $412.24
Q2 2015	16,501,541	$6,665,632	$401.33	$368.88 - $432.88
Q1 2015	16,558,763	$6,991,772	$394.14	$334.40 - $480.18
Q4 2014	17,170,693	$5,828,592	$323.51	$290.85 - $361.93
Q3 2014	17,216,631	$5,695,434	$329.72	$298.31 - $349.00
Q2 2014	17,258,311	$5,441,718	$300.97	$272.02 - $322.25
Q1 2014	17,502,106	$5,353,369	$317.43	$270.62 - $358.89
Q4 2013	17,777,602	$4,970,120	$258.65	$221.07 - $298.82
Q3 2013	17,968,172	$4,326,017	$223.81	$203.55 - $248.95
Q2 2013	18,246,809	$3,926,713	$213.68	$191.80 - $242.64